With the development of electronics and chip packaging technologies, a heat flux intensity of an electronic product trends to increase rapidly. Continuously enhanced functions, seeking for an extremely compact volume, miniaturization, and thinning-down are important competitive powers of a. terminal product. Especially for a wireless data card employing Third Generation (3G)/Fourth Generation (4G) technologies at present, natural heat dissipation is required; however, in a case of the maximal transmit power (Pout=Pmax), the heat flux intensity even exceeds 120 W/L, and thus rationally up-rating heat design is necessary for the development of the electronics and chip packaging technologies. In fact, the terminal product is characterized by: a short life, which generally lasts 3 years to 5 years; a low thermal reliability requirement, in which a certain failure rate is permitted, and an average failure rate is generally 1% to 5%; and in a close relation with a consumer. FIG. 1 is a statistical probability distribution of a transmit power of a wireless terminal product. In the design idea, the wireless terminal product should meet the requirements of above 95% of users, de-rating design is generally not used for element heat design, and up-rating design is even used. Obviously, for a high heat-flux intensity terminal product, risk control is a critical technology.
The work characteristic of a radio frequency element as an analog electronic element is greatly influenced by the temperature. Therefore, a common solution is to dispose a temperature sensor unit in or close to the radio frequency element, so as to monitor the temperature of the radio frequency element such as a Power Amplifier (PA). In the design and production stages, a temperature compensation form is finished according to a test result. In a practical application, the transmit power is modified and compensated according to a reported temperature result. However, the temperature sensor unit must be located in or close to the radio frequency element, the measurement range is limited, and a required measurement range of thermal protection of a PA chip, a Subscriber Identity Module (SIM) card, a User Identity Model (UIM) card, a Universal Subscriber Identity Module (USIM) card, a Micro Secure Digital (MicroSD) card cannot be provided. A heat vulnerable point or vulnerable element is closely correlated with the product design, in a conventional method (for example, a temperature sensor unit is disposed in or close to a PA or a Power Management Integrated Circuit (PMIC)), a corresponding relation between the temperature sensor unit and a protected point is required to be deduced to determine the temperature of the protection point, time delay effect under the dynamic power consumption of a product is very obvious, and an erroneous report easily occurs. During normal working, the temperature reported by the temperature sensor unit is required to be continuously monitored. When the temperature reaches an alarm/shutdown threshold, software/hardware starts an alarm/shutdown related action. After shutdown or disconnection from a network, the temperature of the product drops rapidly, so as to ensure that the thermal reliability requirement of an element is satisfied. The shutdown temperature threshold is depended on the thermal design requirements, and de-rating or up-rating design may be used; however, the de-rating design is generally used, so as to ensure that the chip junction temperature does not exceed a permitted level commercially promised by a manufacturer.
A specific manner in which a temperature sensor unit performs thermal protection and power control on an element includes three-stage protection of a power supply management chip. For example, a temperature sensor unit is disposed in a PMIC chip, the temperature of the PMIC temperature sensor unit is read in running, and certain operations are executed when a certain threshold is reached:
(1) breaking off when the temperature Tj reaches 110° C.;
(2) breaking off and entering a lower power consumption mode to disable non-essential functions when the temperature Tj reaches 130° C.; and
(3) powering off by the PMIC when the temperature Tj reaches 150° C.
However, in the procedure of implementation of the present invention, the inventors find that the prior art has the following problems. In a practical network, the temperature is an accumulated effect of power consumption and time. Due to the existence of multi-path effect and interference, the transmit power may change rapidly, as shown in FIGS. 2a and 2b. The rapid power change means that the temperature sensor unit changes with the power consumption change. In a case of short circuit of the temperature sensor unit, the temperature is considered to be very high, and considered to be very low in a case of open circuit, and great fluctuation of the temperature reported by software occurs in a case of intermittent short circuit and open circuit. In addition, what is processed by the temperature sensor unit is an analog signal, an analog signal in a Printed Circuit Board (PCB) may be interfered by other signals in routing, thus causing an erroneous report and erroneous protection resulting from fluctuation of the reported temperature, as shown in FIG. 3. In a practical application, due to the rapid change of the transmit power, the interference is intensified, thus causing an erroneous report and erroneous protection as shown in FIG. 4.